(1) Field of the Invention:
This invention relates to a process for producing a ground melt. According to the process of the present invention, combined effects of the control of ionic strength, employment of additives and separation and dehydration by centrifugation makes it possible to grind fish bodies even as such to thereby give an excellent ground meat superior in the jelly strength (i.e. the gel strength) to conventional ones. Thus marine products can be utilized more effectively.
(2) Description of Prior Art:
Conventionally the production of ground fish meat is effected by refining minced meat; leaching said minced meat with water; and treating the same with a rotary strainer, a refiner and a screw press successively.
Further, leaching with NaCl for dehydration and decoloring and with Ca.sup.2+ and Mg.sup.2+ for dehydration is sometimes effected in a conventional process for producing ground fish meat.
However in these conventional processes, ground fish meat can be produced only from minced meat. That is to say, it is practically impossible to produce ground fish meat not only from round or whole fish bodies but also from semidresses which are obtained by removing the internals from fish bodies, dresses which are obtained by further removing the heads therefrom, fillets which are obtained by further removing the bones therefrom, and skinless fillets which are obtained by further removing the skin therefrom. There has been attempted to produce ground meat from semidresses and dresses in order to elevate the yield and to save labor. However the ground meat thus obtained has poor properties and/or hardly gels unless starch is added thereto. Further cruschyma meat is completely dissolved without forming any gel. This is because the activities of fish meat proteins other than salt-soluble ones as gelation inhibitors (enzymes), which are particularly high in the cases of round fish bodies to fillets, cannot be inhibited. Furthermore there are some reasons therefor such that the prolonged treatment is liable to be accompanied by inhibition of gelation; that an increase in the treatment temperature accelerates the inhibition of gelation; that there has been established no appropriate method for grinding and fractionating (filtering) fish bodies or tissues in a highly moisten system; and that salt-soluble proteins in fish meat ground to the myofibril level cannot be recovered with a rotary strainer and a screw press.
Relating the points as discussed above, only limited fishes including Alaska pollack, croaker, sardine, mackerel and pike conger are available as raw materials in conventional processes for producing ground fish meat. Thus other marine products such as pectoral rattail, deep-sea rattail, capp, krill, cuttlefish, trepang and prawn cannot be utilized therein.
In addition, in conventional processes for producing ground meat, an insufficient fractionation of salt-soluble proteins results in the contamination of the obtained ground meat with a small amount of water-soluble proteins and substrate proteins, which makes it impossible to obtain excellent ground meat mainly comprising salt-soluble proteins affecting the gel properties and having a high jelly strength. Namely a conventional process for producing ground meat comprises solid phase separation wherein water-soluble proteins are removed mainly by leaching a raw material with water followed by treating the same with a rotary strainer. However some portion of salt-soluble proteins would be eluted during the leaching step or flow from the strainer. Furthermore the separation of the water-soluble proteins with the rotary strainer is extremely insufficient. Then, in a conventional process for producing ground meat, the fish meat from the above step is further treated with a refiner to thereby remove substrate proteins therefrom. However this treatment, which is rough filtration, cannot completely separate the substrate proteins. In addition, it is impossible to completely remove gelation inhibitors from the fish meat thereby since this treatment is effected on muscle bundles and cannot remove the water-soluble proteins.
Furthermore the following facts make it impossible to obtain excellent ground meat by conventional processes. Namely significantly high evolution of heat caused by treating a number of continuous or uncontinuous muscle bundles with a rotary strainer and a refiner several times and further with a screw press for a prolonged period once to several times results in a rise in the temperature of fish meat proteins which are unstable to heat to thereby denature the same. In addition, it is necessary to rapidly remove fish meat proteins other than salt-soluble ones since they act as enzymes inhibiting gelation. However the prolonged treatment, i.e., one to three hours in the conventional processes lowers the activities of the salt-soluble proteins, which brings about denaturation of the fish meat. Further a ground fish meat product free from fishy smell and having a preferable taste and a white color is highly valued from the commercial viewpoint. However conventional processes can hardly give such a ground meat product of a high commercial value because of an insufficient removal of blood, water-soluble proteins and chromo-proteins.
It is further preferable that a ground meat product contain a constant amount of moisture. However it is difficult to maintain the moisture content of a ground meat product produced by a conventional process constant since the moisture content thereof significantly varies depending on the freshness of the minced meat employed as a raw material, the treating procedure and the presence of Ca.sup.2+ and Mg.sup.2+.
Furthermore salt-soluble proteins escaping from the rotary strainer or screw press in a conventional pprocess for producing ground meat cannot be recovered, which lowers the yield of the salt-soluble proteins and makes it impossible to relieve the drainage load.
Furthermore, since leaching of fish meat with NaCl for dehydration and decoloring and with Ca.sup.2+ and Mg.sup.2+ for dehydration, which is sometimes carried out in the final step of a conventional process for producing ground meat, is effected on muscle bundles, the effects thereof are yet insufficient. Thus the purpose and effects thereof are not evident.
In order to solve these problems accompanying conventional processes for producing ground meat, Japanese Patent Laid-Open No. 11762/1981 proposed a process for producing a myofibril jelly which comprises grinding animal myofibril in water or a liquid phase in the same of larger amount as that of the myofibril and applied a centrifugal force of 3,000 G or more to the protein suspension thus obtained.
However fish bodies are not ground as such by this process for producing a myofibril jelly. Further it is not always possible to produce an excellent ground meat having a sufficiently higher jelly strength (i.e. gel strength) than conventional ones thereby.
There is no systematically established method for masking i.e., deodorizing food, particularly marine products. Thus traditional techniques mainly with the use of natural materials are applied thereto. For example, conventional techniques therefor include the use of burdock for masking the muddy odor of dojo (Misgurnus anguillicaudata); the use of milk for masking fishy smells; and the flavoring effects of koji-mold and spices.
However these masking agents are added to food, in particular marine products, usually not at the stage of raw materials but at the final seasoning step.